Take an ingredient as commonplace as the lemon. You may think you know all there is to know about cooking with it. You’ve juiced it, zested it and given it a twist. But have you chopped up its flesh and added it to a salad? Or tempura battered a slice to eat atop butternut squash and buckwheat polenta (see recipe), or roasted it for a salad of tomatoes and pomegranate seeds?

This is the beauty of London-based chef Yotam Ottolenghi’s recipes. You are treated to such revelations; new uses for ingredients you are well acquainted with. You are also invited to cook with ingredients that may be less familiar, such as barberries, dakos (Cretan crispbread) and kashk (made from fermented milk, yogurt or whey). These are just a few of the globally-inspired vegetarian ingredients Ottolenghi explores in his new cookbook, Plenty More (Appetite by Random House, 2014).

“I came across the tempura lemon slice in Boston where I was spending some time a couple of years ago,” Ottolenghi says in an interview. “It was a moment of revelation with a very familiar ingredient. I think it’s just really exciting. We can take all of these ingredients and really put them in a completely new context.” He started his exploration of vegetable-centric cooking in The New Vegetarian column for The Guardian (1996 to 2010). The column inspired a book, Plenty (Chronicle Books, 2011), which changed the way many home cooks looked at vegetables and their varied uses. Then there was the immensely popular Jerusalem: A Cookbook (Appetite by Random House, 2012), which he co-wrote with business partner and fellow native Jerusalemite Sami Tamimi.

While Plenty focused on groups of plant-based ingredients (e.g. Roots, Green Things, Pulses), Plenty More looks at different techniques used to construct the dishes – Tossed, Braised, Baked – with a few of Ottolenghi’s new favourite ingredients added to the mix. Some of them are familiar, such as miso and tamarind, which he found he was using increasingly to infuse his vegetable dishes with more flavour. But others hadn’t made many appearances in Ottolenghi’s recipes prior to Plenty More. “One example is pandan leaf, which is an Asian ingredient that is almost like the equivalent of vanilla in the Far East, where it infuses sweets, cakes and desserts all the time,” he says. “I use it again in this context in my book to infuse sweets and desserts. It’s very hard to describe but once you’ve tasted it you recognize it. It’s a wonderful, harmonious, sweet flavour that goes with fruit and creams and tofu and all sorts of things that are used in Asian desserts.”

A new savoury ingredient that Ottolenghi uses in Plenty More is black garlic, which originated in Korea and is made by slow cooking and drying the bulb over several weeks, resulting in caramelized cloves. “It really loses all its harsh garlic flavour. It turns into something black licorice-y, almost cocoa-y in flavour,” he says. “I started using it a lot for marinades, for dressings; you need to kind of dilute it into something else but it’s absolutely fantastic to create a sense of depth of flavour with vegetables but also with meat.”

Although he isn’t advocating a meat or fish-free diet, Ottolenghi thinks people have woken up to the flavours that can be achieved with vegetables, herbs, grains, legumes and fruit. The foods and flavours of his hometown, as explored in Jerusalem: A Cookbook, gave Ottolenghi a good foundation to build on when it came to exploring the diversity of plant-based foods. “In the Middle East, where I grew up, vegetables and pulses are the main staples and not meat,” Ottolenghi says. “So it was a good starting point to cooking with vegetables, but I probably knew much less than I know today. And I’ve travelled a bit and I’ve read a lot and I’ve come in contact with cooks from all over the world, so I’ve really managed to expand my horizons on many fronts.”

More Asian and North African ingredients are included in Plenty More, and Ottolenghi’s “real fascination with Persian cooking” is seen in recipes such as Iranian Vegetable Stew with Dried Lime. “I tend to borrow from various places around the world. But also, I think my mind opened about various combinations with ingredients that I had already known; putting together things that I might not have put together in the past,” Ottolenghi says. “If you only look at the cover of Plenty More, you’ve got the rhubarb and the beets and the blue cheese [Beet and Rhubarb Salad]. I doubt that I would have used that combination eight years ago. My mind has really opened up to the possibilities with vegetables and those kinds of new combinations.”

Preheat the oven to 400°F/200°C. Trim the top and bottom off the butternut and halve lengthwise. Scoop out and discard the seeds and cut each half into 3 long wedges, skin on. Place the wedges in a large roasting pan with all the remaining squash ingredients and ¾ teaspoon salt, coating the butternut well with the aromatics. Bake for 50 minutes, turning the butternut pieces every 10 minutes or so and spooning the juices over them, until the squash is cooked, golden brown, and starting to crisp on top. Add a little stock during cooking if the pan is drying out.

Meanwhile, to make the polenta, put the kasha in a small baking pan and toast in the oven at the same time as the squash for 5 minutes, or 10 minutes for plain groats. Remove and crush lightly with a pestle and mortar.

In a large saucepan over high heat, combine the milk, stock, herbs, lemon rind strips, ¾ teaspoon salt, and a pinch of white pepper. Bring to a boil and then turn the heat to low and whisk in the polenta and buckwheat. Using a wooden spoon, stir every few minutes for 35 to 40 minutes, until the polenta is thick and cooked. If it is getting too thick, add a little water. At the end of the cooking, stir in the butter. The polenta should be thick but runny enough to fall off the spoon easily. Cover the top of the polenta with plastic wrap to stop a skin from forming and leave somewhere warm.

To make the tempura, mix together the flour and cornstarch, then whisk in the soda water until the mixture is smooth and runny. Sit the bowl over ice for 45 minutes.

Pour oil to a depth of 1¼-inches/3-cm into a saucepan and heat to about 320°F/160°C. Dip the lemon slices into the batter and fry for 2 to 3 minutes, until golden and crispy. Remove with a slotted spoon and sprinkle immediately with salt.

Place a spoonful of warm polenta on each plate and lay a squash wedge across it, adding a mix of the baked aromatics on top. Finish with a tempura lemon slice and serve at once.

Apricot, Walnut, and Lavender Cake

Apricot, Walnut, and Lavender Cake from Plenty More by Yotam Ottolenghi.

Place the butter, oil, superfine sugar, and almonds in a stand mixer and beat on medium-high speed until light and fluffy. Add the eggs in small additions and continue to beat until well incorporated. Fold in the walnuts, flour, vanilla, lemon zest, 1 teaspoon of the lavender, and ⅛ teaspoon salt.

Line the base and sides of a 9-inch/23-cm cake pan with parchment paper. Pour in the cake batter and level the top. Arrange the apricot halves, skin side down and slightly overlapping, over the top, right to the edge. Bake in the oven for 70 to 80 minutes, covering with aluminum foil if the top starts to brown too much.

While the cake is baking, make the icing. Whisk together the confectioners’ sugar and lemon juice to get a light, pourable icing, adjusting the amount of sugar or juice if needed. As soon as the cake comes out of the oven, brush the icing on top. Sprinkle the remaining ½ teaspoon lavender over the top and leave the cake to cool before serving.